Workers at the Animal Place sanctuary in Vacaville load rescued hens into cages for their ride to the Oakland airport to catch a plane headed for the East Coast.

Photo: Michael Macor, San Francisco Chronicle

Workers at the Animal Place sanctuary in Vacaville load rescued...

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The leghorn chickens await the trip.

Photo: Michael Macor, San Francisco Chronicle

The leghorn chickens await the trip.

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Josh Trenton (left), Simone Hasenbein, Debbie Ramsey and Susan Larsen round up the chickens at Animal Place in Vacaville.

Photo: Michael Macor, San Francisco Chronicle

Josh Trenton (left), Simone Hasenbein, Debbie Ramsey and Susan...

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David Phinney, care coordinator at Animal Place, holds one of the leghorn chickens headed for an East Coast sanctuary.

Photo: Michael Macor, San Francisco Chronicle

David Phinney, care coordinator at Animal Place, holds one of the...

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The chickens are carefully loaded into cages that hold 10 hens for transport to Oakland airport.

Photo: Michael Macor, San Francisco Chronicle

The chickens are carefully loaded into cages that hold 10 hens for...

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The hens at the Animal Place sanctuary in Vacaville, Calif. on Wednesday Sept. 4, 2013, are loaded into cages, ten per cage for transport to the airport. 1,200 chickens which were rescued from a egg farm will leave tonight from Oakland International Airport flying to animal sanctuaries on the east coast after they were found living in terrible conditions.

Photo: Michael Macor, San Francisco Chronicle

The hens at the Animal Place sanctuary in Vacaville, Calif. on...

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One of the hens has a look around from inside the transport cage, at the Animal Place sanctuary in Vacaville, Calif. on Wednesday Sept. 4, 2013, as the chicken will soon travel to the airport. 1,200 chickens which were rescued from a egg farm will leave tonight from Oakland International Airport flying to animal sanctuaries on the east coast after they were found living in terrible conditions.

Photo: Michael Macor, San Francisco Chronicle

One of the hens has a look around from inside the transport cage,...

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Toni Okamoto, the social media coordinator and volunteer, Josh Trenter, at the Animal Place sanctuary in Vacaville, Calif. on Wednesday Sept. 4, 2013, load the chickens into cages for transport to the airport. 1,200 chickens which were rescued from a egg farm will leave tonight from Oakland International Airport flying to animal sanctuaries on the east coast after they were found living in terrible conditions.

Photo: Michael Macor, San Francisco Chronicle

Toni Okamoto, the social media coordinator and volunteer, Josh...

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The hens at the Animal Place sanctuary in Vacaville, Calif. on Wednesday Sept. 4, 2013, are still laying eggs are they are prepared for transport to the airport. 1,200 chickens which were rescued from a egg farm will leave tonight from Oakland International Airport flying to animal sanctuaries on the east coast after they were found living in terrible conditions.

It started as a small effort by a chicken rescue group to save hens from an untimely death at a California egg farm. But an anonymous donor's generous gift has turned that modest quest into an unusual and apparently unprecedented mission: taking 1,200 chickens on a transcontinental flight to safety.

A few weeks ago, the fluffy, white leghorn chickens were living in cramped wire cages at an egg farm, doomed - like so many millions of other hens in the state - to the gas chamber because they no longer laid jumbo-size eggs.

But by Thursday morning, this group will have completed their flight aboard a cargo plane from Hayward to upstate New York, where they will be taken by nine sanctuaries to live out their days pecking at bugs and roosting in the shade.

The poultry airlift was arranged by Animal Place, a Vacaville farm animal rescue group, which acquired the hens - plus 1,800 others - in late July after making arrangements with the farm owners.

Ordinarily, hens at egg farms face a grim fate: euthanized at age 2 or 3 when their egg-laying capabilities begin to wane. Until then, they typically live in small cages with up to eight other hens, often under artificial lights that prompt them to lay up to five times more eggs than hens in a natural environment, according to both animal rights advocates and the egg industry.

California's Proposition 2, which voters passed in 2008, will improve hens' living conditions somewhat when it goes into effect in 2015. The new law mandates that hens have enough room to turn around and lie down in their cages without brushing against other hens.

"We've made a lot of progress over the past 10 years and we're making even more progress," said Mitch Head, spokesman for the United Egg Producers, which represents most large egg farms in the country. "The farmers care about the animals. The hens and eggs are their livelihood."

The industry has already increased the amount of space each hen occupies. A decade ago, hens were confined to an average of 40 square inches. Now the average is 67 inches, he said.

A tough life

But meanwhile, many of the 18 million hens living in California egg farms have a tough existence. Some live on farms where they're allowed to range freely, but millions of others spend their lives jammed into wire cages so cramped they cannot turn around or stretch their wings without butting against other birds, Head and Marji Beach, educational director for Animal Place, said.

At some farms, the tips of chicks' beaks are snipped so they don't peck each other, and their feet become shredded from the wire cages.

Then, when they start laying eggs less frequently or the size of the eggs begins to shrink, they're placed in large containers, euthanized and sent to landfill. Because most of their energy has gone into egg laying, they're too small and skinny - about half the size of other hens - to be processed into food, Head said.

"People want to buy jumbo eggs, and it's not economical to keep hens that are laying smaller eggs," he said.

Since 2010, Animal Place has rescued about 12,000 hens from farms around California. Some stay at the group's sanctuaries in Vacaville and Grass Valley, but most are adopted by the public. The hens still lay eggs, but closer to the rate of a regular hen, about 50 to 60 a year, Beach said.

Garden helpers

"They're great little gardeners," said Beach. "They're good for eating bugs, providing compost, aerating the soil. And they're great companions, as good as a cat or dog."

In late July, Animal Place was set to take 2,000 hens - about the maximum the group could handle - from a farmer Beach would not identify because he had requested confidentiality. But then, thanks to an anonymous donation of $50,000, Animal Place was able to charter a plane for the East Coast so more hens could be rescued.

In all, nine farm animal sanctuaries in upstate New York and other eastern states offered to take a total of 1,200 hens.

"We're so excited. We've never done anything like this before," said Jenny Brown, director of the Woodstock Farm Animal Sanctuary in the Catskills. "This is an amazing opportunity. Of all the animals at factory farms, nobody suffers worse than egg-laying chickens."

'Doing chicken things'

The hens were in sorry shape when they arrived at Animal Place in late July, Beach said.

They had so little muscle or skeletal strength they could barely stand, and their wings were injured from beating against the cage walls. Their nails had grown 2 to 3 inches long because they had never set foot on the ground.

"They're adorable little white birds, though," said Beach. "These days they're hanging out in the sun, scratching around in barns, doing chicken things."

Animal Place staff have been giving them vitamins and treating them for parasites, but mostly letting them rest.